[Mailman-Users] announce only with attachments

[Donny Brooks]

The way we use mailman is mostly for announce only lists. So I have it configured as per this site: http://wiki.lunarpages.com/MailMan_Announce_Only_Mailing_List. With that we only send out notifications to the patrons who have signed up for the various lists. How would I allow attachments and/or inline HTML with images? We have one list in particular where we are building two new museums and the staff would like to send picture updates to the lists. Should disabling convert html to plain text be enough? Am I missing any other settings? 
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Donny B.